Control for feeding device



MW :21 [HIM no N NNNNNN OR FIG. 1

April 1968 I A. A. FLICK 3,375,961

CONTROL FOR FEEDING DEVICE Filed March 23, 1966 2 Sheets-Sheet :5

0 ll l n m m m m Q O) Q 'U U o NV r2 JOIJ I I O O C? b1r2b2 e1r2e2 INVEN'TOR Antonius Augusrinus Flick FIG. 2

United States Patent 3,375,961 CONTROL FOR FEEDING DEVICE Antonius Augustinus Flick, Rotterdam, Netherlands, assignor to Hunter Douglas International, Ltd. Filed Mar. 29, 1966, Ser. No. 543,764 Claims. (Cl. 22632) The invention relates to a method and device for the electrical correction of errors, occuring in markings on band material fed to a working machine, which material is stopped each time at the working station for carrying out a working; which markings serve to determine the right position of the material at a working, as well, as to the product obtained with this method and/ or device.

It is usual to detect a marking error in such a method and such a device and thereafter to carry out a correction of the feeding mechanism of the material. The signalling of the markings is mostly carried out therewith before the feeding mechanism in the moving direction of the material after which a correction of the detected error is carried out directly, but said correction will then not be carried out on that portion of the material, of which the marking error is measured. No right correction is obtained thereby.

Furthermore the nearly inevitable slip of the material is not taken into account in said method, when passing the material through the feeding mechanism. Said slip occurs because the material is moved with steps very quickly.

By the abovementioned inexact correction a considerable percentage of inexactly worked material occurs.

Moreover it appeared not possible to work printed material e.g. to punch it, with a high velocity to 300 workings per minute, e.g. when punching crown caps.

With the method and device according to the invention said great loss of inexactly worked material is eliminated in such manner that after at detecting of a marking error the correction of said error is only carried out just before the part of the material comprising said wrong marking arrives at the working station.

Among other applications the invention is therefore highly suitable for the manufacturing of metal objects, such as crown caps by punching of preprinted marked metal e.g. aluminum band or strip material at high speed.

According to the invention the signalling of a marking error is also carried out between the members, feeding the material directly to the working station, and the Working station itself.

In the method according to the invention is further taken care that the signalling of a marking supplies an electrical signal, causing an error signal after comparison with a reference signal, reproducing the theoretical exact marking said error signal being stored in a memory, having the correction of the error only occur just before the part of the material with a wrong marking arrives at the working station.

Preferably, for the increase of the exactness, the duration of time of the signal, coming from the signalling, and of the reference signal is practically of the same length.

According to the invention the time of the occurrence of the reference signal can be controlled in order to have the signal of the marking and the reference signal coincide at a correct marking of the material to be worked, so that no error signal need be stored in the memory.

Preferably a detection of an error in a marking is carried out one step of the material before the working station. Owing to this only two error signals need to be stored in the memory, viz a first error signal, which must be kept till the following step, during which step the measured material arrives at the working station and a second error signal, which must be kept until the next step. In this way the memory is constructed in the most simple way. It will be clear that a detection of more than 3,375,961 Patented Apr. 2, 1968 one step before the working station, the memory must be extended further in order to retain more error signals.

It is still remarked that by positioning the signalling device after the feeding members of the material, the occurring slip need not be taken into account in said members.

The application of an electrical memory allows to use a maximum time of a single step causing a mechanical slow device to operate, which functions to cause the ultimate mechanical correction members carrying out their correction.

According to the invention it is possible to supply a signal from the memory within one step of the band material and to have e.g. the correction take place via lifting magnets and the correction members.

An example of the invention will now be elucidated by means of the drawing.

FIGURE 1 shows schematically an operating machine with the signalling device, the memory and the correction members together with applied auxiliary means.

FIGURE 2 shows the circuit of the memory and of the lifting magnets, which operate the mechanical correction members.

In FIGURE 1 is shown an operating machine 8, comprising a main shaft 7 and a fly wheel 9. In the main shaft 7a crank is schematically shown by way of example for the operation of a punch. Said punch or other working means must carry out a working on a material 1 at a working station 27, said material being quickly fed to the working station 27 by means of feeding members, such as rolls 18 and 19 to stop there for a moment in order to be subjected to a working. The material 1 carried away along discharge members such as rolls 20 and 21 in the direction of the drawn arrow. The material is passed along stepwise.

The fast running material 1 is marked by markings in such a way that for each marking a step of the material occurs. One of the most important working problems is that the prints and/ or marks of the material show errors. As a consequence thereof the working is not carried out in the right position, but somewhat before or after said position, so that e.g. the punch punches in a wrong place.

According to the invention a light source 2 and a photocell 3 are used the light source dropping its light on a marking, after which the photocell 3 observes the sensing of the marking by the light ray and a signal is delivered from the photocell. The error and therewith also the size and direction of the marking error is now expressed by comparing the signal coming from the photocell, said signal being supplied to a comparing and an amplifying member 4, with a reference signal, which is also sup plied from a signal transmitter 5, such as an electromagnetic switch, indicating the theoretical exact marking to the comparator 4 through the conductors 22.

After the observation of a marking and comparison with a reference signal, an error signal is obtained at the output of the comparator 4. Said comparator 4- comprises a plurality of outputs, such as 28a, 28b, 28c and so on. The sense or direction of the error signal that is: the feature whether the marking on the material to be worked in positive or negative direction shows an error, determines whether a signal occurs on channel 28a or on channel 28b. The size of the error signal determines whether said signal is only passed through channel 28b or also through channel 280 and so on to the member 25.

In the memory 25 the error signal, supplied through one or more of the channels 28a, 28b, 28c and so on, is stored, after which it is transmitted through the output conductors 24 to one or more of the lifting magnets 15, 16, 17 and so on at the desired time, depending on the switch members S1, S2 and S3, showing a special relation with the revolution of the main shaft 7 of the machine 8, said magnets putting the correction members in a member 6 into operation for changing the stroke of the material feeding mechanism e.g. as by actuating the stroke of a carriage of said feeding mechanism of the working machine 8, thus though the marking of the material 1 to be worked, being not quite exact, said material arrives at the working station 27 with exactly its right portion. The present invention is particularly favorable at its application in combination with a correction mechanism, as described above using lifting magnets to actuate correction members influencing the stroke of the supply mechanism. Said correction mechanism including lifing magnets does not from a part of the present invention. Said correction mechanism, however, may be of any desired construction. Its actuation of the correction members can take place in anyknown way, e.g. hydraulically, pneumatically, and so The above-mentioned switch members S1, S2 and S3 are brought into a switched-on or a switched-off condition, depending on their respective cam discs 12, 13 and 14. The cam discs each make a half revolution in said embodiment of the invention at a single revolution of the main shaft 7 and are coupled therewith through a gearing for example toothed wheels 10 and 11.

Furthermore it can be seen from FIGURE 1 that the opening and closing of the switch members S1, S2 and S3 is transmitted to the memory via the conductors 26.

The signal transmitter 5 only transmits the reference signal through the conductors 22 to the comparator 4, depending on the revolutions of the main shaft 7. The reference signal is only given once per revolution of the main shaft 7.

As already remarked, the time of the occurence of the reference signal can be changed with respect to the start of a revolution of the main shaft 7 in order to have the photocell signal through the conductors 23 at the observed exact marking on the material to be worked coincide with the reference signal through the conductors 24, so that no error signal will be delivered from the output of the comparator 4 to the memory 25. It will be appreciated that in that case at the next step of the material to be worked (if measured one step before the working station 27) said material to be worked will arrive exactly at the right place underneath the punch of the machine 8, thus exactly at the working station 27.

From the above it results moreover that by the quick electrical storage of the error signal in the electrical memory, which preselects also directly one or more of the lifting magnets 15, 16 and 17, the mechanical slow correction members in the mechanism 6 substantially have at their disposal a whole step of the material from the measurement by the photocell 3 until the working station 27 in order to carry out the correction in case a marking error is measured.

The operation of the memory can be seen from the circuit of FIGURE 2. In FIGURE 2, apart from the memory, are also indicated the lifting magnets 15, 16 and 17 as well as the switch member S1, S2 and S3 with their appertaining cam discs 12, 13 and 14. In FIGURE 2 also are illustrated the supply channels 28a, 28b and 28c, which can supply an error signal from the comparator 4 to the memory.

In said memory (25 in FIGURE 1) is shown an auxiliary relay R, of which the winding can be excited, by example with a direct voltage by closing the switch S1. Said switch is only closed when its cam disc 12 by rotation of the main shaft 7 has turned its portion, drawn at the righthand (in FIGURE 2), to the left. However in the position drawn in FIGURE 2, the switch S1, is opened. In this case the auxiliary relay R is not excited. However the relay contacts r1, 12 and r3 in the lower relay group D, E, F are closed. When by rotation of the cam disc 12 the switch S1 closes, the auxiliary relay R is excited and the said contacts r1, 1'2 and r3 in the lower relay 4.- group D, E, F will be opened and the contacts r1, 12 and r3 in the upper relay group A, B, C of FIGURE 2 are closed.

At each error signal supplied from the comparator the cam disc 12 made each time a half revolution, in which the respective error signal will find closed either the lower set of contacts r1, 1'2 and r3 or the upper set of contacts r1, 1'2 and r3. Thus this relates to each time of a step of the material to be worked, because at each step thereof an error signal is supplied into the memory.

If an error signal arrives for example through the channel 28b in FIGURE 2 from the camparator 4 of FIGURE 1, said error signal will find the contact r2 open in the upper relay group, but will find the contact r2 of the auxiliary relay R closed in the lower group D, E, F, so that the error signal can pass via the resistance 33 and the winding of relay E by which said relay E operates shortly.

The relay E as well as the relays D and F of the lower group of relays in FIGURE 2 comprises a holding contact el and a wipe out contact e2. For each of the relays of the lower group and for each of those of the upper group A, B and C there is a third contact at one of the lifting magnets 15, 16 and 17, whereas the relays of said upper group each comprise also a holding contact a1, b1 or 01 and a wipe out contact a2, b2 or 02.

To the relay E, shortly operated by the error signal on the one channel 28b, also appertains the contact e3 with the lifting magnet 16. By the short response of E, its holding contact e1 closes. The relay E will remain operated by this after the error signal on the channel 28b is terminated. The operated relay E closes also its wipe out contact e2, which applies after some time by closing the switch S2 owing to the rotation of its cam disc 13, the positive voltage on the lower side of the winding of the relay E also to the upper side of said winding through the wipe out contact e2. However, this takes some time.

At first the contact 3 is still closed at the excitation of the relay B so that a preselection with regard to the lifting magnet 16 is carried out by the memory. After a. further rotation of the main shaft 7 the cam disc 14 of the switch S3 will rotate further, so that the switch S3 closes its upper contacts (in FIGURE 2) and thus closes a circuit from the negative terminal of the voltage source via the closed contacts e3 and the lifting magnet 16 to the positive terminal of said voltage source. By this the lifting magnet 16 is excited. Said lifting magnet 16 operates the correction member, arranged in the part 6 in FIGURE 1, by which the stroke of the carriage is adjusted on the exact value for movement of the material 1 to be worked and said material is stopped at the exact working station 27.

It will be appreciated that, as said above, the lifting magnet is preselected via the contact e3. Thereafter the switch S3 is closed in the required position, after which the correction members, which are mechanically slow, will have enough time at the step to be carried out from the place where the measurement took place to the working station 27 to carry out the corresponding correction.

After the preselection by the memory of the contact 03 of the lifting magnet 16 the switch S3, however, is not directly switched, but first the common switch S1 is switched in the closed position by the cam disc 12. Then the relay R will operate and the contacts r1, r2 and r3 thereof in the lower relay group D, E and P will be opened thereby and the contacts r1, r2 and r3 of the auxiliary relay R at the upper relay group A, B and C will be closed, so that said upper relay group is prepared to receive a next error signal from the comparator 4 as a consequence of a measurement by the photocell 3. In the meantime the cam disc 14 has rotated so far that the switch S3 is no longer closed in its lower position. At a further rotation of the cam disc 14 the switch S3 closes in its upper position, by which the preselected lifting magnet 16 will now be excited (by reason of the first mentioned error) (on channel 2815, the relay E of the lower group and its third contact e3). The memory had thus stored the error signal through the channel 28b until said time of switching of the switch S3 by the preselection of the lifting magnet 16. By said switching of S3 and the excitation of the lifting magnet 16 the correction mechanism will come into operation.

Now will be assumed that an error signal arrives on channel 28a. This causes a short excitation of the relay A through the contact r1 and the resistance 29, so that its holding contact a1, its wipe out contact 02, and its third contact a3 are closed at the lifting magnet 17 and remain closed by the holding contact a1. The lifting magnet 17 is now preselected by this.

Immediately after said preselection of the lifting magnet 16 the switch S1 will be opened and the auxiliary relay R is de-energized, by rotation of the cam disc 12, so that now the lower group of relays D, E and F is prepared to receive a next error signal.

After said switching of S1 the real correction occurs of the error, which caused the error signal on the channel 28b.

Thereafter the switch S3 proceeds to its lower closed position by rotation of the cam disc 14, so that the second preselected lifting magnet 17 is excited via the contact a3 of the relay A of the upper relay group. Shortly after said switching of the switch S3 the cam disc 13 operates the wipe out switch S2, which is then closed in its righthand position and applies a positive voltage via the wipe out contact e2 to the upper side of the winding of the relay E and would also apply the same voltage to the upper side of the relays D and F (through their wipe out contacts d2 and f2) if these would also have been excited by the first error signal (if this would have been greater or have had opposite direction). Owing to all this all relays of the lower groups will thus be de-energized.

The same wiping out occurs when the switch S2 is in its left-hand position in FIGURE 2, by which all relays A, B, C of the upper group are wiped out at a next step via the wipe out contacts a2, b2 and c2.

The cam disc 12 also has made another half revolution and the common switch S1 is opened again, so that in the lower relay group D, E and F the three auxiliary contacts r1, r2 and r3 of the auxiliary relay, R are closed (without excitation), so that said lower group is free. again to register and store the third marking error of the material 1 to be worked.

From the above it will be appreciated that each time after the preselection of a lifting magnet at its excitation by switching of the switch S3, the appertaining correction members will carry out their operation.

The correction mechanism 6 has thus suificient time for its operation, whereas after switching of S3 (lifting magnet 16 excited, correction mechanism 6 will operate) prior to which S1 has already prepared the other relay group A, B, C, the next error may certainly appear through the channel 28a in said relay group A, B, C in order to preselect the lifting magnet 17. Thereafter first S1 switches to the relay group D, E, F andonly then the real mechanical correction is carried out.

It appears herefrom that the correction occurs Within one revolution of the machine.

It will be appreciated that, if no error signal arrives through the input channels 28a, 28b, 280, of the memory 25, that is when the comparison of the photocell signal with the reference signal does not indicate a marking error, the respective relay group is not excited, no lifting magnet is preselected and thus no operation of correction members will occur either and the working machine 8 causes the material 1 to be worked to arrive at the working station 27 according to said exact marking.

From the occurence of the first error signal in the channel 28b (relay group D, E, F excited, the lifting magnet 16 preselected, e3 closed) until the clearing or wiping out of the group D, E, F by S2 the preselection contact e3 is closed. In the meantime, after S3 has excited the lifting magnet 16, the second error is received on the channel 28a and is passed to the relay group A, B, C, so that the lifting magnet 17 is preselected by closure of the preselection contact a3. From said moment up till the moment that $2 wipes out the first error signal from the other group D, E, F, both preselection contacts e3 and a3 are closed.

The same occurs, if a same error in the marking of the material 1 to be worked occurs during .a longer time, the markings being thus wrongly arranged on the material 1 and said error remains occurring. After excitation for example of the lifting magnet 16 for example by excitation of the relay E, again a subsequent, but equal marking error is supplied through the same channel 28b, but now to the other relay group and namely to the relay B, positioned above the relay E. As appears from the drawings the third contact of said relay B, being contact b3, is also arranged at the lifting magnet 16. Thus on switching of the switch S3 the lifting magnet 16 should first be de-energized, because the preceding error via the contact e3 is interrupted by said switch S3, after which the lifting magnet 16 again should operate immediately by closing the switch S3 in the other position through the other contact b3.

However, it will be appreciated from the above de scribed closing of preselection contacts e3 and a3 simultaneously during some time, that when a same error occurs repeatedly, for example the preselection contacts e3 and b3 are closed simultaneously during some time. In that time the cam disc 14 switches the switch S3, so that the lifting magnet 16 remains operated. Also the mechanical position of the correction member is maintained, so that no reciprocating movements of said mechanical correction members occur.

From the circuit of the memory 25 in FIGURE 2 it will be appreciated that a greater number of relays per relay group can be applied in case there also are provided a greater number of input channels 28a, 28b, 28c, and so on, which depends again on the number of lifting magnets and the number of correction member to be operated and on the desired exactness of the correction.

If desired, the arrangement can further be made still more extensive, by extending the number of relay groups. According to the shown example the signalling device 2, 3 is working one step before the working station. Therefore two relay groups in FIGURE 2 are needed because it is desired to store each time one error signal until the second comparison and error registration take place. If a signalling device 2, 3, for example should have to work three steps before the working station so three relay groups are needed. However, it appears that for a good exactness, in practice two relay groups are suflicient as is shown in FIGURE 2. It has appeared that a correction can be made up to 0.1 mm. or less, which means a very great exactness with respect to existing machines. The result is that with the method and the device according to the invention substantially no loss of material occurs.

It is still remarked to this that the lower limit for the absolute error magnitude to be corrected is adjusted in the comparing device 4.

The output channels of the device 4 are then first responded by this, when the error surpasses a predetermined and preselected value.

Preferable to control the mechanical correction members lifting magnets such as 15, 16 and 17 are used given as examples in the present invention.

As an example of a fast running machine of the abovementioned type can be indicated that a machine with 300 workings per minute still work with a sufficient exactness when applying the method and device according to the invention.

I claim:

1. In apparatus for detecting and correcting spacing errors on a strip of material being stepped sequentially past a work station at which operations are performed on it at operating points denoted by markers on the strip, including feeding means in front of said work station for feeding said strip thereto, means for detecting, during a given sequential step of said strip, an error in the spacing of a given operating point marker from the immediately preceding operating point marker, and means responsive to detection of such error for correcting the length of the terminal step which carries the operating point corresponding to the given marker to the work station for properly positioning the operating point indicated by said given marker at the work station, the improvement wherein said error detecting means includes first means for generating a first signal representative of the zero-error location of said given marker second means for generating a second signal representative of the actual location of said given marker, a comparator for generating an output signal representative of the dilference between said first and second signals, and a memory for storing representations of the comparator output signals; and said correcting means includes step control means responsive to a representation stored in the memory for varying the length of said terminal step in accordance with the stored representation.

2. Apparatus as defined in claim 1 wherein the memory includes a plurality of sections each for storing a comparator output signal corresponding to a respectiv sequential step, and switching means for switching sequential comparator output signals to respective ones of said sections in a predetermined order, said step control means being operative during said terminal step.

3. Apparatus as defined in claim 2 wherein the comparator output signal is an n-bit parallel binary signal and said memory includes n input conductors corresponding to said n bits, each of said memory sections having n= binary storage elements corresponding to said n bits, corresponding ones of said n storage elements in each section being connectible by said switching means to a common one of said n input conductors and being responsive to a signal thereon to assume an ON state; and said correction means include n correction members each responsive to the ON state of one or more corresponding storage elements connected to a common input conductor for assuming a CORRECT state.

4. Apparatus as defined in claim 3 wherein each of said binary storage elements includes holding means for maintaining it in the ON state after termination of the signal on the input conductor connected to it, release means responsive to a release signal for resetting the storage element to its OFF state, and a third means in circuit with the correction member associated with the binary storage element for setting the correction member to its CORRECT state.

5. Apparatus as defined in claim 4 including a shaft connected to step said strip past the work station; encoder means for cyclically generating signals representative of the angular position of the shaft, one of said signals being a switching signal and fed to said switching means to control switching of said comparator output signals, a second of said signals being a release signal and fed to each release means in a specified memory section; said correcting means including means responsive to a third such encoder signal for delivering a correction signal corresponding to those correction members which are in the CORRECT state to the step control means.

6. Apparatus as defined in claim 5 wherein each binary storage element is a relay and each of said holding means, release means and third means associated therewith is a make/ break contact controlled thereby.

7. Apparatus as defined in claim 6 wherein said encoder means operates in a cycle, each such cycle including a switching signal for preselecting a memory section, a third encoder signal subsequent to the switching signal for delivering a correction signal, and a release signal subsequent to the third signal for releasing all relays in the memory section selected by the switching signal.

8. Apparatus as defined in claim 7 wherein the encoder means comprises three cams driven by saidshaft, and a switch controlled by each said cam for generating a respective one of the switching, third and release signals.

9. Apparatus as defined in claim 8 wherein the memory has two sections and each said cam is shaped to set its associated switch to two states during said cycle.

10. Apparatus as defined in claim 9 wherein said comparator output signal represents the magnitude and direction of said diiference.

References Cited FOREIGN PATENTS 816,184 7/1959 Great Britain.

ALLEN N. KNOWLES, Primary Examiner. 

1. IN APPARATUS FOR DETECTING AND CORRECTING SPACING ERRORS ON A STRIP OF MATERIAL BEING STEPPED SEQUENTIALLY PAST A WORK STATION AT WHICH OPERATIONS ARE PERFORMED ON IT AT OPERATING POINTS DENOTED BY MARKERS ON THE STRIP, INCLUDING FEEDING MEANS IN FRONT OF SAID WORK STATION FOR FEEDING SAID STRIP THERETO, MEANS FOR DETECTING, DURING A GIVEN SEQUENTIAL STEP OF SAID STRIP, AN ERROR IN THE SPACING OF A GIVEN OPERATING POINT MARKER FROM THE IMMEDIATELY PRECEDING OPERATING POINT MARKER, AND MEANS RESPONSIVE TO DETECTION OF SUCH ERROR FOR CORRECTING THE LENGTH OF THE TERMINAL STEP WHICH CARRIES THE OPERATING POINT CORRESPONDING TO THE GIVEN MARKER TO THE WORK STATION FOR PROPERLY POSITIONING THE OPERATING POINT INDICATED BY SAID GIVEN MARKER AT THE WORK STATION, THE IMPROVEMENT WHEREIN SAID ERROR DETECTING MEANS INCLUDES FIRST MEANS FOR GENERATING A FIRST SIGNAL REPRESENTATIVE OF THE ZERO-ERROR LOCATION OF SAID GIVEN MARKER SECOND MEANS FOR GENERATING A SECOND SIGNAL REPRESENTATIVE OF THE ACTUAL LOCATION OF SAID GIVEN MARKER, A COMPARATOR FOR GENERATING AN OUTPUT SIGNAL REPRESENTATIVE OF THE DIFFERENCE BETWEEN SAID FIRST AND SECOND SIGNALS, AND A MEMORY FOR STORING REPRESENTATIONS OF THE COMPARATOR OUTPUT SIGNALS; AND SAID CORRECTING MEANS INCLUDES STEP CONTROL MEANS RESPONSIVE TO A REPRESENTATION STORED IN THE MEMORY FOR VARYING THE LENGTH OF SAID TERMINAL STEP IN ACCORDANCE WITH THE STORED REPRESENTATION. 